US Open champion Emma Raducanu on Tuesday claimed her first victory since her shock triumph in New York as the British teenager beat Polona Hercog at the Transylvania Open in Romania.

Raducanu, 18, recovered from a set down to win 4-6, 7-5, 6-1 after nearly two hours and 30 minutes in the first round in Cluj-Napoca against Hercog, the world number 124 from Slovenia.

Making just her second appearance since the US Open, the 23rd-ranked Raducanu led 4-1 in the first set before Hercog won five games in a row.

The third seed saved a break point at 5-all in the second set and won a lengthy following game on Hercog's serve to force a decider.

Raducanu, born in Canada to parents from Romania and China, dominated the third set to secure her first victory in a WTA event and advance to a meeting with Romania's 106th-ranked Ana Bogdan.

"It means a lot to play in my dad's country," said Raducanu, who delighted the crowd by conducting most of her post-match interview in Romanian.

Raducanu stunned the tennis world at Flushing Meadows by becoming the first qualifier to win a Grand Slam title. 

She had suffered a second-round loss to Aliaksandra Sasnovich at Indian Wells earlier this month in her first outing since the US Open.

"I don't think there is any pressure on me," Raducanu said on Monday. "I feel like everyone should just be a little patient with me.